The 72-year-old actress said on Tuesday's episode of The Ellen DeGeneres Show that she was immediately drawn to Martin as the 40-year-old singer attended Ellen DeGeneres' birthday party with Dakota Johnson.
"I'm going to talk about Chris Martin. He was with Dakota, right? They're a couple," she said. "What I'm saying is he's gorgeous. You know, that face got better with time. He was wearing a hat like this [baseball cap]. Oh, it was to die for."
Keaton said she was attracted to Martin but didn't realize who he was until a couple days after the party.
"I didn't know who he was. I saw him and I noticed that he was gorgeous. I had no idea until a couple days later when someone said, 'Did you know?'" she recalled. "How could I not have known it was him?"
Martin and Johnson attended DeGeneres' 60th birthday party Feb. 10 amid dating rumors. People reported the pair were spotted holding hands and spending time with Martin's ex-wife, Gwyneth Paltrow, and her fiancé, Brad Falchuk, at the bash.
"Gwyneth is happy if Chris is happy. She only wants the best for him," a source previously told Us Weekly.
"She trusts his judgement and knows he's smart about his decisions and who he spends time with," the insider added. "She leaves it at that. She doesn't scrutinize his choices of who he dates."